Light sources suitable for illuminating the interior of a building are usually divided between artificial lighting (e.g. electric bulb) and openings communicating directly with the outside.
However, the increase in the cost of energy and environmental constraints render the use of electricity increasingly unsuitable for illuminating the different rooms of a building. Yet the use of artificial lighting is necessary in many rooms where it is impossible to make openings communicating directly with the outside, i.e. particularly the case of rooms situated directly inside a building or in the basement.
Solar energy thus offers the most economical source of lighting available. However, even in rooms provided with windows, said windows are not always sufficient to provide sufficient lighting. This is particularly the case in classrooms where artificial lights are constantly switched on as the exterior light arrives laterally and not uniformly.
In order to address these different problems, technical solutions have been developed in order to convey exterior light in all rooms with the comfort of artificial lighting (direction and constant power).
Of all these technologies, light wells are the most widely used. A light well usually comprises a collection zone, a transmission zone and a diffusion zone.
The collection zone is advantageously positioned on the roof of the building. In simple systems, it may adopt the form of a roof window or a dome. In more complex systems, it may also consist of optical concentrators suitable for collecting and concentrating solar radiation and comprising for example a set of mirrors and/or lenses.
The light collected is consequently concentrated at the intake of light transmitting members, these members being suitable for transmitting light to the diffusion zone with minimum loss while retaining the specificity of natural light.
One of the drawbacks of light wells is that the efficiency thereof may drop significantly due to poor positioning of the intake of the transmitting members in relation to the optical concentrator. Indeed, if the light collected is not correctly concentrated at the intake of light transmitting members, it is obvious that loss will inevitably occur in terms of the light transmitted.